puntloos Posted January 31, 2023 Share Posted January 31, 2023 So.. I am aware ASHPs lose a lot of efficiency above a certain temperature, so I imagine my hot water tank to sit at say say 50C. But here's a use case: if you have a 38C warm bath, and the water starts to cool down, you might want to top up. The most water-saving method of doing this is of course having the top-up water as hot as possible, so 65-ishC would perhaps be ideal while keeping somewhat safe. Are inline 'water heat boosters' (presumably electric) a thing? Something that would on demand take 50C water to 65? And is this a good idea or am I overthinking things? Link to comment Share on other sites More sharing options...
SteamyTea Posted January 31, 2023 Share Posted January 31, 2023 Depends how much you pay for water and waste really. You can get inline heaters think @joe90 had one and sold it to someone on here. 1 Link to comment Share on other sites More sharing options...
puntloos Posted January 31, 2023 Author Share Posted January 31, 2023 Fair. Perhaps the cost of a water heater creates so much waste (just by its production) that the overflowing lukewarm water lost occasionally (I don't linger in baths that often anyway) is better for the world. But still, if this is one 25 quid bobbin one puts into a void somewhere.. Link to comment Share on other sites More sharing options...
PeterW Posted January 31, 2023 Share Posted January 31, 2023 Siebel Eltron make 10kW inline heaters but it’s irrelevant for a bath as they have to have anti-scald prevention to limit the output to 45°C Link to comment Share on other sites More sharing options...
JohnMo Posted January 31, 2023 Share Posted January 31, 2023 1 hour ago, puntloos said: top-up water as hot as possible, so 65-ishC It's just illegal, so no issues really - that sort of temperature can kill a child and do adults no good either. 1 second at 60 to cause 3rd degree burns! Recent case where child had run a bath unsupervised and jumped in. Not sure if child died or just badly burned, but mom/dad ended up in prison I believe. 1 Link to comment Share on other sites More sharing options...
Conor Posted January 31, 2023 Share Posted January 31, 2023 We heat our water to 45c and no issues topping up a bath when it cools a bit. Link to comment Share on other sites More sharing options...
Marvin Posted January 31, 2023 Share Posted January 31, 2023 Because we sometimes have high temperature water storage all our hot water supplies from the tank are regulated to a max of 45C. Link to comment Share on other sites More sharing options...
joth Posted January 31, 2023 Share Posted January 31, 2023 Rather than run water to top-up, just heat the tub to stop it cooling down in the first place. simples. https://www.aquaticabath.co.uk/products/627722004484-aquatica-true-ofuro-tranquility-heated-japanese-bathtub 2 Link to comment Share on other sites More sharing options...
puntloos Posted February 15, 2023 Author Share Posted February 15, 2023 Interesting points here. Yes 65C water, as it exists in (gas-heated) cylinders is super hot and can certainly do damage, but - handwavingly, if you have a tub of say 35C water, to get it to 38C by using 44C water you need to replace (aka throw away) half of the bath. Heated bath is intruiging @joth but that particular one is certainly way too weird 1 Link to comment Share on other sites More sharing options...
JohnMo Posted February 15, 2023 Share Posted February 15, 2023 Easy fix, shower, or don't spend ages in a bath 2 Link to comment Share on other sites More sharing options...
puntloos Posted February 15, 2023 Author Share Posted February 15, 2023 5 minutes ago, JohnMo said: Easy fix, shower, or don't spend ages in a bath Thanks JohnMo, I think I'll first investigate this option Link to comment Share on other sites More sharing options...
Iceverge Posted February 15, 2023 Share Posted February 15, 2023 How about bonding an electric UFH mat onto the underside of the tub backed by some roll insulation. You might even be able to avail of a thermostatic function, should work for those who like to read entire novellas in the tub. Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 15, 2023 Share Posted February 15, 2023 Jesus. I leave you lot alone for a few hours and now we have a bath with a heated blanket. 65°C out of a bath tap is no longer permissible. That’s lunacy. The most a bath hot tap or mixer can have coming out of it is 46°C, above that is an instant b-regs failure. So “NO”. 3 Link to comment Share on other sites More sharing options...
SteamyTea Posted February 15, 2023 Share Posted February 15, 2023 27 minutes ago, puntloos said: Thanks JohnMo, I think I'll first investigate this option Fine for coffee, an abomination for tea. 1 Link to comment Share on other sites More sharing options...
Jenni Posted February 15, 2023 Share Posted February 15, 2023 My heat pump installer said to just run the immersion / legionnaires cycle on bath night. No bath here yet but hoping that'll be OK when the time comes as I like a long hot bath. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 15, 2023 Share Posted February 15, 2023 11 minutes ago, Jenni said: I like a long hot bath 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 16, 2023 Share Posted February 16, 2023 On 15/02/2023 at 21:16, Jenni said: My heat pump installer said to just run the immersion / legionnaires cycle on bath night. He's an idiot. That cycle should be performed early hours of the morning, ideally in line with an EV car charging ( cheap rate ) tariff, and scheduled as to purposefully avoid scalding someone. 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 16, 2023 Share Posted February 16, 2023 Time for a reality check people!!! Get a thermometer and put it in the bath when you think, "ooh, that's just right", eg just before you pass out and then turn the hot tap back off.. Please post that temp here and lets see who ACTUALLY needs these ridiculous DHW temps. 4 Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 16, 2023 Share Posted February 16, 2023 🦞 Link to comment Share on other sites More sharing options...
Marvin Posted February 16, 2023 Share Posted February 16, 2023 My guess is 44C Link to comment Share on other sites More sharing options...
Gill Posted February 17, 2023 Share Posted February 17, 2023 I like a toasty soak but I'll have to guess as our tub is too big and nukes the full tank for a half bath. 41 would be my guess. I'm sure we got warned visiting Japan about temps over 43 in the onsen. Those were too hot for a long dip. Reminds me... Need to lookup compact Japanese style short deep tubs for when I get round to sorting the bathroom in 2025. 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted February 17, 2023 Share Posted February 17, 2023 4 hours ago, Gill said: 41 would be my guess. I'm sure we got warned visiting Japan about temps over 43 in the onsen. Those were too hot for a long dip. I think I heard that, or something similar. Link to comment Share on other sites More sharing options...
jayc89 Posted February 17, 2023 Share Posted February 17, 2023 On 15/02/2023 at 13:44, Nickfromwales said: Jesus. I leave you lot alone for a few hours and now we have a bath with a heated blanket. 65°C out of a bath tap is no longer permissible. That’s lunacy. The most a bath hot tap or mixer can have coming out of it is 46°C, above that is an instant b-regs failure. So “NO”. If the cylinder is heated to anything above that, how would you reduce the temp coming out of a non-mixing bath tap? I've only measured the temp at our kitchen tap (as it's the furthest away from the cylinder) and that was ~ 55c. One bath's in the same room as the cylinder so I'd expect it to nearly match the stat temp. Link to comment Share on other sites More sharing options...
Nickfromwales Posted February 17, 2023 Share Posted February 17, 2023 56 minutes ago, jayc89 said: If the cylinder is heated to anything above that, how would you reduce the temp coming out of a non-mixing bath tap? I've only measured the temp at our kitchen tap (as it's the furthest away from the cylinder) and that was ~ 55c. One bath's in the same room as the cylinder so I'd expect it to nearly match the stat temp. I put a thermostatic mixing valve on the hot outlet of the cylinder, set to 550C, and if the bath tap is not thermostatic, another TMV has to go in to cap the bath at 46oC. "We have the technology" 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted February 17, 2023 Share Posted February 17, 2023 1 Link to comment Share on other sites More sharing options...
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